Period or Cohort Effects? Surfaces of Average Annual Improvements in Mortality

Roland Rau, University of Rostock

What drives mortality change? While some argue that current conditions shape mortality (period effects), other propose that events early in life or the cumulative experience throughout life determines mortality (cohort effects). The novelty of our study is to approach this question by Lexis surface maps of average annual improvements in mortality. Our result is that within the countries from the Human Mortality Database, there is no uniform pattern which shaped the development of mortality in recent decades. For instance, the former Eastern part of Germany experienced strong positive period effects since reunification in 1990 whereas Russia suffers from negative period effects already for several decades. Life expectancy of Danish women stagnated for almost 20 years after 1980 due to strong effects of birth cohorts born between the two World Wars. In contrast, we found also strong positive cohort effects of women and men born around 1940 in several countries.